How to pass user input data to variables to solve formula

I known that to compute series of number, we have to

puts #{(2+19)/3}
we have answer = 7

How to enter inputs from keyboard to do math, for variables as number 2
above, such as

puts #{(var +19)/3}

I tried puts var, printf #{var}, var=STDIN, STDOUT.puts var, all without
error but no answer!

It is working OK, if I have a given var with a value number:
var=2
puts #{(var +19)/3}
I will have answer = 7

Otherwise, if we put:

STDOUT.puts var
puts #{(var +19)/3}

error is: undefined local variable or method

Thank You

Can Le wrote:

I known that to compute series of number, we have to

puts #{(2+19)/3}
we have answer = 7

How to enter inputs from keyboard to do math, for variables as number 2
above, such as

puts #{(var +19)/3}

I tried puts var, printf #{var}, var=STDIN, STDOUT.puts var, all without
error but no answer!

It is working OK, if I have a given var with a value number:
var=2
puts #{(var +19)/3}
I will have answer = 7

Otherwise, if we put:

STDOUT.puts var
puts #{(var +19)/3}

error is: undefined local variable or method

Thank You

print “Enter a value?”
var = gets
puts (var.to_i+19)/3

try this, i hope it helps you.

Thank you